A deflection ring of the type mentioned in the opening paragraph is known per se. For example, in U.S. Pat. No. 5,057,738, filed by Applicants, a description is given of a number of deflection rings which are made from an MgZn-ferrite material which also comprises a certain quantity of Li and Mn. In this Patent, a description is also given of a cathode ray tube comprising a deflection unit having such a deflection ring.
The known deflection ring has disadvantages. It has been found that when this ring is used in a cathode ray tube, heat dissipation in the deflection unit occurs at room temperature, at induction levels of 20 to 25 mT and frequencies of 16 kHz or multiples thereof. This dissipation leads to an undesirable increase of the temperature of the tube and hence to a reduction of the life of the surrounding electronic components of the tube.